Warner



(No Model.)

E. P.' WARNER. THREE WIRE MULTIPLE SWITCH BOARDSYSTEM.

No. 428,189. Patented May 20.1890.

'E i 91m UNITED STATES PATENT OFFICE.

ERNEST P. VARNER, OF CHICAGO, ILLINOIS, ASSIGNOR TO THE VESTERN ELECTRIC COMPANY, OF SAME PLACE.

THREE-WIRE MULTIPLE SWITCH-BOARD SYSTEM.

SPECIFICATION forming part of Letters Patent No. 428,189, dated May 20, 1890. Application tiled December 10,1888. Serial No. 293,140. (No model.)

To all whom it may concern:

Be it known that I, ERNEST P. WARNER, a citizen of the United States, residing at Ohicago, in the county of Cook and State of Illinois, have invented a certain new and useful Improvement in Three-Wire Multiple Switch- Board System, (Case 19,) of which the following is a full, clear, concise, and exact description, reference being had to the accompanying drawings, forminga part of this specification.

My invention relates to telephone-exchange apparatus of the multiple type, in which the boards are divided into two groups, aconnecting device being provided for each of-say, half of-the lines on each board of one of the groups, and a connecting device for each of the other half of the lines upon each of -the boards of the other group. In adivided multiple switch-board system of this class we have halt1 the lines connected with one group of boards according to the multiple plan, and

- are increased.

the other half of lines connected with another group of boards. Each line of division lis provided with a terminal upon one of the boards of group 2, and each of the lines of division 2 is provided with a terminal on one of the boards of group l. Signaling apparatus has also been provided, so that each subscriber may signal Vat will to either one or the other of the two groups of switch-boards. The lines, say, from l to 3,000, will form the lirst division and be connected with the rst group of switch-boards, While the lines from 3,000 to 6,000 would form the second division and be connected with the second group of boards. A subscriber knowing the number of the line with which he Wants connection sends in one of two signals, accordingly as the line wanted is above or below 3,000-that is, he sends the signal to the group of boards upon each of which the line wanted has aterminal. I-leretofore in such divided systems it has been proposed to use metallic circuits for the different subscribers. In such systems the expense and diiiiculties at the exchangeoffice are multiplied as the number of lines It is therefore desirable to provide a special signal-circuit in addition to the talking-circuit of each subscriber. I have sometimes termed my system the three-wire system on this account, though it will be apparent that my invention is notin all respects limited necessarily to those systems in which each subscriber is provided with two wiresthat is, a metallic circuit for talking. It will also appear that my invention is not limited to any particular test system-that is, it is not limited to any particular apparatus for finding out when a line is called for whether said line is connected or in use. Ishall therefore describe my invention as embodied in a divided multiple system employing metallic talking-circuits, and for clearness of description and illustration shall refer onlyincidentally to the test system.

Speaking generally, my invention consists in connecting the different telephone-lines with switches on each of the boards of one group and with a switch on one of the boards of the other group, and, in connection with each telephone-circuit, running a special signalcircuit from each subscribers station through signal devices, as annunciators, one at least on one of the boards of each of the groups, the signal device of each group or division in each signal-line being adapted to respond to current ot' different polarities or character.

In the accompanying drawings, Figure l is a diagram illustrative of two subscribers stations connected with a telephone-exchange by circuits embodying my invention. 1 Fig. 2 is a detailed sectional view of an ordinary spring-jack switch, a loop-plug inserted therein,such as are used preferably at the exchangeoffice. v

The multiple switch-boards at the exchangeoffice are Vin two divisions or groups,group A consisting of three boards a b c', and group B consistinglikewise of three duplicate boards a2 b2 c2. Subscribers station l is connected with spring-jack switches CZ e f', one being on each of the boards of group A, and also with a spring-jack switch g upon one of the boards of group B-in this instance board c2. This station l is provided with a connecting device on each of the boards of group A and with another connecting device upon one of the boards of group B.

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The talking-eircuit or telephone-line of station l is a metallic circuit h, the limb h', when the telephone is removed from the switch, extending from the switch through the telephone and through the spring and contact of each of the switches d e f g of the line, while the other branch 71.2 extends to the ring or test piece of each of said spring-jack switches. As shown in Fi 2, the two branches h and h2 may be connected with the difterent strands ot the cord of the loop-plug when the plug is inserted.

It will be observed that I have included no annuneiator or other device for signaling the central oiice in the metallic circuit 7L, or rather in each of the limbs 7L h2, which when united form the metallic circuit.. I provide a special wire 'L' for signaling. This wire t' extends from the subscribers station through an annunciator k on one of the groups and through another annunciator t2 on one of the boards of the other group. These annunciators k k2 in the signaling-circuit t' should be polarized to respond to current in different directions.

At the subscribers station I provide a generator Z, in connection with a switching dcvice or pole-changer Z', adapted to loop the generator into the circuit t' to send currentin the proper direction to operate the annunciator k or the annunciator 72. The key Z2 is included in the circuit of branch or limb h2 at station 1, and is so placed with respect to the contact or terminal of signal-circuit -i that when depressed circuit i will be closed to ground through the switching apparatus Z and the generator the direction of the current through annunciator depending upon the position of switch Z', which may be moved at the will ot' the user to the position required. Ie have, then, station l connected by a telcphone-line with a dilerent switch of each of the switch-boards of group A and with a switch on one of the boards of group B.

In addition to the telephone-line we have a signal-circuit wire which extends to an annuneiator upon one board of each ot' the groups of boards, and these ann unciators are polarized to respond each to current in one direction only, and are so placed in circuit that only one will be operated by current of a given direction.

The circuits ot station l and their connections with the different switch-boards of the exchange as thus described, may be considered the same as those of other stations. Station l would be considered as belonging to the first division or group A of the exchange. This first division might embrace the stations numbered from l to 3,000, the remaining stations of the subscribers being numbered from 3,000 to 0,000.

As shown in Fig. l, station 2 may be cousidered as one of the subscribers stations of the second division. The telephone-line m of this station is run in the same manner heretofore described with respect to telephoneline 71/ of station l--that is to say, telephone line m includes a spring-jack switch on each of the boards of group B, and a spring-jack switch on one of the boards of the first group A. These spring-jack switches cl2 cfz, distributed on the boards of group B, and the spring-jack switch g2 upon board b of group A, may be of the construction shown in Fig. 2. The circuit m will be found open normally at switch g2. A loop-plug inserted in any one of the switches cl2 c2 f2 g2 may be used to connect the telephone-line m in metallic circuit with any other line with which connection is desired. The switching apparatus or pole changer, the generator, and connections may be the same at station 2 as herctofore described with respect to station l.

on one board of each of the divisions or i groups B A.

I have thus described the manner of connecting the telephone-lines and the signal- `lines with the different groups or divisions of lswitch boards of the divisional multiple switch-board system.

I wil now describe the manner ol' signaling the central oilice and making the connections between the different teleliihone-lines. Suppose subscriber l wishes connection with subscriber 2. He depresses key Z2 and places the pole-changing switch Z in position to send current from the generator lover signal-wire 1I in proper direction to operate annunciator k2. The operator at board c2, seeing annum ciator 7a2 fall, will at once insert a loop-plug, as loop-plug p, into answering spring-jack g ot line 71., which is numbered to correspond with the annuneiator 7a2. The operators telephone. at board c2 is then brought into the circuitI by bringing the operators telephone-switch into the position shown, to bridge the telephone in a circuitfcrossing from one cord to the other, which is a wellknown method of making the connection with the operators telephone and is generally termed bridging across. It will be observed that the signal is sent in over the signal-wire t', and that the operator on seeing the signal loops the telephone into the telephone-line z, thus completing the circuit between the subscribers station and the operator, it being understood that the subscriber on sending the signal will immediately take down his telephone, so as to bring his telephone into the circuit of line 71.. The operator at board c2, upon receiving the order for subscriber 2, inserts the other plug p of the pair into the spring-jack switch f2 ot' line m. Having inserted plug p in spring-jack f2 the operator, by depressing key q, brings the generator' into circuit, so as to send current over line m and ring the bell at subseribers station 2. The operator then disconnects her telephone and is ready for the next call. When the subscribers are through talking, the one who sent in the call-that is to say,

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in this instance subscriber l-will send cur-` rent over signal-wire c' in direction to throw down again shutter 7a2. This will be the disconnecting-signal and the operator pulls out the plugs p p.

In case subscriber 1 wished a connection with any one of the subscribers of the first division, current would be sent over line c' in the other direction so as to operate the shutter 7s. rlhe operator thereupon at board c will proceed to make the connection ordered. It should be observed that whenever two telephone-lines are connected together no clearing-out annunciators are included in their united circuit.

In telephone-exchange systems the greatest part of the troubles from induction arise from the signaling current. By providing independent signal-circuits forth'e subscribers I am enabled to separate the telephonecrcuit so far from the signal-circuits in running the wires that no injurious induction can take place.

I have not described any test system for determining whether a line wanted or called for at one board is connected or in use at any other ot the boards, since such test systems are well known and a number of them might be readily adapted to my three-wire system ot' its circuits.

Having thus described my invention, I claim as new and desire to secure by Letters Patentl. The combination, with a subscribers station, of a telephone-line extending through spring-jack switches, one on each of a group or division of multiple switch-boards, and one on one board of the other group or division of switch-boards, and a signal-wire eX- tending from the subscribers station through annunciators or signal devices, one on one board of each of the groups or divisions of boards, said annunciators or signal devices being polarized and connected to respond to currents of opposite polarities and switching apparatus and a source of electricity at the subscribers station, whereby current may be sent in either direction over the signal-wire, and the telephone of the subscriber brought into the telephone-circuit, substantially as and for the purpose specified.

2. A telephone-exchange consisting of multi ple switch-boards in two divisions or groups, subscribers stations divided in corresponding groups, each subscribers station being connected by telephone-lines with a switch or terminal on each of the boards of its division and with a switch or terminal on one of the boards of the other division, and a special signal-wire for each station connected with an annunciator on one board of each of tbe\ divisions or groups, said annunciators bei@ polarized to respond to current of different polarities, substantially as and for the purpose specified. 3. The combination, with a telephone-line extending from a subscribers station to a group of multiple switch-boards and to a single board of another group at a central station, of a special signal-wire extending from the same subscribers station to two oppositely-polarized annunciators located at boards of the said groups, switching apparatus, a source of electricity, and atelephone and bell at the subscribers station, and switching apparatus, a source of electricity, and a telephone at one board in each group of the multiple switch-boards, whereby the subscriber may signal the central office over the special signal-wire, and the operators at the central office may signal the subscriber over the telephone-line, and whereby the telephones may be connected together for conversation without including in their circuits either the bell of the subscriber or the annunciator at the central oiiice.

et. The combination, with the subscribers outtit, consisting of a telephone, bell, generator, and switching apparatus, ofatelephoneline consisting of two branches or limbs, one branch or limb being connected through the spring and contact of each of several switches distributed on different multiple switchboards of one group and one switch or spring-jack upon one board ot another group of switch-boards, the other branch or limb being connected with the frame or test piece of each of said spring-jack switches, a special signal-wire extending from said subscribers station through two polarized annunciators placed on diiferent boards ot' the two groups of switch-boards and connected in circuit to respond to current of different polarities, respectively, and an operators'outfit consisting of a telephone and switching apparatus at each of the boards at which the polarized annunciators are placed, whereby the subscriber may signal at will at either of said switchboards, and whereby connection maybe made between the operators telephone at either of the boards and the subscribers telephone, substantially as and for the purpose specified.

In witness whereof I hereunto subscribe my name this 29th day-of September, A. D. 1888.

ERNEST P. WARNER.

Vitnesses:

GEORGE P. BARTON, .CHAs G. I-IAWLEY.

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